Log debug info at Debug level

All logs under the DEBUG flag in this file are (properly) logging
at Log.d(), except for one at Log.e(), claiming an "E"rror in the
system.

We change that to Log.d() to avoid confusing folks debugging other
issues who are looking through logcat.

Bug: 181080516
Test: TreeHugger
Change-Id: I4ff6fd9a6dd6caa7516620125762b7c0442b74b4

packages/SystemUI/src/com/android/systemui/navigationbar/NavigationModeController.java

@@ -132,7 +132,7 @@ public class NavigationModeController implements Dumpable {
             Settings.Secure.putString(mCurrentUserContext.getContentResolver(),
                     Secure.NAVIGATION_MODE, String.valueOf(mode)));
         if (DEBUG) {
-            Log.e(TAG, "updateCurrentInteractionMode: mode=" + mode);
+            Log.d(TAG, "updateCurrentInteractionMode: mode=" + mode);
             dumpAssetPaths(mCurrentUserContext);
         }